package awk.lock;

import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/*
 * 1. ReadWriteLock : 读写锁
 *
 * 写写/读写 需要“互斥”
 * 读读 不需要互斥
 *
 */
public class TestReadWriteLock {

    public static void main(String[] args) {
        final ReadWriteLockDemo rw = new ReadWriteLockDemo();

        new Thread(new Runnable() {
            public void run() {
                rw.set((int)(Math.random() * 101));
            }
        }, "Write:").start();

        for (int i = 0; i < 100; i++) {
            new Thread(new Runnable() {
                public void run() {
                    rw.get();
                }
            }).start();
        }
    }

    static class ReadWriteLockDemo {

        private int number = 0;

        private ReadWriteLock lock = new ReentrantReadWriteLock();

        //读
        public void get() {
            lock.readLock().lock(); //上锁

            try {
                System.out.println(Thread.currentThread().getName() + " : " + number);
            } finally {
                lock.readLock().unlock(); //释放锁
            }
        }

        //写
        public void set(int number) {
            lock.writeLock().lock();

            try {
                System.out.println(Thread.currentThread().getName());
                this.number = number;
            } finally {
                lock.writeLock().unlock();
            }
        }
    }
}
